The present invention relates to the continuous reactivation of activated carbon particles, and more particularly to a fluidized-bed reactor for the continuous reactivation of activated carbon particles.
Activated carbon particles are used as adsorption media for cleaning of gases and liquids. During the adsorption cycle, during which the carbon particles remove contaminants from the gases or liquids, the carbon particles become contaminated with more and more of the retained contaminants and thus become less and less effective for the intended purpose. After a certain time, their effectiveness has decreased to such a point that the carbon particles must be reactivated, i.e., must be freed of the contaminants, in order to be capable of operating again in the intended manner.
Carbon particles used for cleaning of liquids are usually poured onto beds of sand or gravel in an adsorber through which the liquid is passed. When these carbon particles require reactivation, they are flushed out of the adsorber either by means of air or by means of water, or else they are mechanically removed from the adsorber. The trouble with this is that this approach makes it impossible to preclude the removal of at least small quantities of sand, gravel and/or sludge from the adsorber, which then travel with carbon particles into the reactor in which the carbon particles are to be regenerated. During the regeneration in the reactors, particularly in fluidized-bed reactors, there is simultaneously a separation of the carbon particles from the quantities of sand, gravel or the like, which have traveled with them and which settle on the bottom of the fluidized bed reactor, i.e., on the perforate wall on which the fluidized bed is established. Over a period of time, the thus settled undesirable components accumulate and ultimately lead to interference with the proper reactivating operation. The reason for this is twofold in that the accumulated sand or gravel reduces the usable volume of the reactivating reactor, and further in that the sand or gravel tends to settle and compact, clogging the openings in the bottom wall on which the fluidized bed is supported, so that the bed is no longer properly capable of being fluidized and the reactor must be disassembled and cleaned.
A prior art proposal has been made to overcome these problems, in that a fluidized-bed reactor is used which is provided with concentric baffles arranged in the reactor chamber which are provided with openings for the passage of material and through which the material must pass in a labyrinthine fashion. However, contrary to earlier expectations, this approach has not been found to be satisfactory because even with this type of construction, clogging will ultimately occur, again in particular clogging of the openings in the bottom wall on which the fluidized bed is to be established and maintained. The reactor must then be taken apart and cleaned, because of the rather complicated construction resulting from the use of the aforementiond baffles, this is even more difficult and time consuming than in the earlier-mentioned type of reactor.